add is_online property to Worker and WorkerStatus models for online status tracking

cluster/models.py

@@ -54,6 +54,14 @@ class Worker(models.Model):
     created = models.DateTimeField(auto_now_add=True)
     uuid = models.UUIDField(default=uuid.uuid4, editable=False, unique=True)
 
+    @property
+    def is_online(self):
+        try:
+            return self.workerstatus.is_online
+        except WorkerStatus.DoesNotExist:
+            return False
+
+
 
 class WorkerStatus(models.Model):
     worker = models.OneToOneField(Worker, on_delete=models.CASCADE)
@@ -70,3 +78,11 @@ class WorkerStatus(models.Model):
     updated = models.DateTimeField(auto_now=True)
     created = models.DateTimeField(auto_now_add=True)
     uuid = models.UUIDField(default=uuid.uuid4, editable=False, unique=True)
+
+    @property
+    def is_online(self):
+        from django.utils import timezone
+        from datetime import timedelta
+        if not self.last_seen:
+            return False
+        return self.last_seen >= timezone.now() - timedelta(minutes=10)

templates/cluster/workers_list.html

@@ -54,11 +54,14 @@
                     <span class="text-muted">{% trans 'Not set' %}</span>
                 {% endif %}
             </td>
-            <td style="width: 1%; white-space: nowrap;">
+            <td style="width: 1%; white-space: nowrap;" class="{% if not worker.is_online %}text-danger blink{% endif %}">
                 {% if worker.workerstatus %}
                     {{ worker.workerstatus.last_seen|date:"M d, H:i" }}
                 {% else %}
-                    <span class="text-muted">{% trans 'Never' %}</span>
+                    <span class="{% if not worker.is_online %}text-danger blink{% endif %}">{% trans 'Never' %}</span>
+                {% endif %}
+                {% if not worker.is_online %}
+                    <i class="fas fa-exclamation-triangle text-danger blink" title="{% trans 'Last seen more than 10 minutes ago or never seen.' %}"></i>
                 {% endif %}
             </td>
             <td style="width: 1%; white-space: nowrap;">